The present invention applies to technology of demagnetization of objects which are afloat, of transport engineering objects, and can also be used for demagnetization of such items, as turbines, diesels, etc.
The most widely used technical facility for demagnetization of large objects is a multiturn operating winding in the form of a solenoid, ring, frame, etc., supplied with power from an external source and arranged inside a structure into which the object is placed; or it could be fitted around the object for some time.
One known example is a demagnetization stand /Navy international, v, 94, No.6, 1998, p.269-270 which is a round-shape structure, or adit, and the object to be demagnetized is placed inside it. The stand is equipped with operating windings in the form of transverse framing, comprising a solenoid with the length slightly exceeding that of the object.
The drawback of this stand is the necessity for high capital investments required to build the structure plus expenditures for purchasing and mounting of the cables. The total cable length in this case amounts to many kilometres (the operating winding cable length required for a stand of 30 m diameter and 200 m length will be 30xc3x973.14xc3x97200=18, 840 m).
Another known example is stand where the operating windingsxe2x80x94solenoid are made in the form of a ring. Demagnetization is effected by pulling the object through this ring.
Here again large expenditures are required for building a deep-water embankment, a ring to be anchored to the bottom, the cables. Besides, such a stand is not suitable for demagnetization of floating objects with superstructures and masts.
Also well known is a system of ship demagnetization /U.S. Pat. No.4993345, B 63 G 9/00, 19 Feb. 1991 where a cable-type operating winding is applied temporarily around the ship over its waterline in horizontal plane. The winding is kept afloat by buoyancy elements. The ends of operating winding cable are connected to a power source.
The shortcoming of the system is the lack of operating winding fixation at a specified distance from the ship hull, which impairs the quality of demagnetization. The single-turn system does not permit to generate a uniform field over the whole height (depth) of the ship.
Another such system /V. A. Tkachenko. History of Soviet Navy ships demagnetization. L., xe2x80x9cNaukaxe2x80x9d, 1981, p.53/is intended for demagnetization (degaussing) of large objectsxe2x80x94warships; here they fit to ship plating above the waterline a degaussing coil consisting of several turns of cable. The coil is energized with direct current. To measure the magnetic field, a boom with measuring sensors is pulled along under the ship bottom. The boom is installed in one of cross-sections under the ship, its ends are fastened with wire ropes suspended from the buoyancy elements which are afloat at the starboard and port sides of the ship.
The drawbacks of the system are manual winding of the cable and impossibility to obtain the required accuracy of measurements of the ship magnetic field due to oscillations of sensors even at slight seas, to rolling of the ship and buoyancy elements.
It is customary in the world practice to use in operating windings (coils) electric cables with copper cores, and such cables are quite expensive. In temporary application of such operating coils at die objects the sable cannot be used more than 2 or 3 times, as due to multiple bends the electrical insulation fails.
To summerize the essential drawbacks of the demagnetization systems indicated above, these are the need for capital stationary structures and enourmous lengths of cables. When operating cable coils are wound on the object by hand, the labour input and duration of work are quite considerable, which results in the increase in the total demagnetization time. Such systems are not Suitable for demagnetization of transport engineering products, also for such items, as turbines and diesels. The devices for magnetic field measurements at the objects to be demagnetized require futher development.
The most close to the system for warships is a system developed for degaussing of ferromagnetic objects and containing operating coils with rectilinear busbars which are placed so that they make it possible to demagnetize a sea-going ship in three directions. It also contains a power supply unit for energizing of operatying coils, a device for measuring the ship""s magnetic field characteristics and a carrier incorporating the system""s components /FR N 2587969 B 63 G 9/06, 03.04.87/.
However, the above system is not sufficiently unified and mobile which makes its practical use limited.
The goal of the present invention is development of an object demagnetization system which will be free from the drawbacks indicated above.
This goal is achieved by using a ferromagnetic object demagnetization system containing an operating coil with four rectilinear main busbars connected with four jumpers; the busbars are mounted, two on each side, over the whole length of the object, one above the other at a distance determined by the object""s height. The system also contains a power source for energizing the operating coil and a device for measuring the characteristics of the ship""s magnetic field and presentation of initial data for processing of the above field. There is also a carrying device intended for incorporation of the system""s components and constructed from rigidly connected modules with framework made of non-magnetic materials. The power source is located inside the power-generating module, the operating coil and device for measuring the characteristics of the ship""s magnetic field are fitted in the pair of side working modules. The butt face devices are designed to provide rigid connection between the power-generating module and side working modules with the use of movable fixation locks. The jumpers mentioned above are mounted in the butt face devices and provide a possibility for switching-over the ends of main busbars in accordance with specified current direction.
Some essential particular features helped in solution of the set task.
The power source for power supply to the operating winding (coil) has been designed as a strong-current generator, such as unipolar generator.
The main busbars of each side module are also its structural elements.
The side working modules are positioned with a possibility of changing the distance between them by means of mechanical movement and fixation with locks.
The main busbars in the side working modules have been mounted with a possibility of changing the distance between them in height with the aid of a drive.
The side working modules have been designed with a possibility of pairwise connection to increase the length of the main busbars.
The power module and side working modules are provided with an arrangement for their transfer over the land, for instance, using wheels.
The power module and side working modules are made watertight, with a possibility of transportation over water and demagnetization of floating ferromagnetic objects.
The jumpers are mounted with a possibility of switching-over the ends of main busbars with the aim of creating vertical, sloping, horizontal magnetic fields acting on the object and switching-over the power source contacts for changing of magnetic field direction.
Each side working module carries an electromagnetic coil consisting of two frames mounted symmetrically on both sides of the object to be demagnetizad in vertical planes parallel to its axis. A possibility is provided for processing of the ferromagnetic mass concentration area by focused lateral magnetic field in the course of object movement. The current from the power source to the coil frames is supplied with the aid of main busbar elements and conductors laid down in bifilar pattern.
In top and bottom parts of each side working module longitudinal guides are fitted for movement of carriages of mobile components; the sensors of the object""s magnetic field measuring device are mounted on the above carriages and have a possibility of volumetric measurements of the magnetic field over the whole length of the object to be demagnetized.
Within the plane perpendicular to the object""s longitudinal axis a coil is installed with a possibility to process a cylindrical object moving through the coil along the longitudinal axis. The current from the power source is supplied to the coil via the elements of main busbars and conductor laid down in bifilar pattern. The sensors of the device measuring the magnetic field characteristics are located over the coil perimeter.